1. What is a Lumens to Watts Calculator?

Definition: This calculator converts luminous flux (lumens) to power consumption (watts) based on the efficacy of the light source.

Purpose: It helps compare energy efficiency of different lighting technologies and estimate power requirements for lighting projects.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( W \) — Power in watts (W)
• \( L \) — Luminous flux in lumens (lm)
• \( E \) — Luminous efficacy in lumens per watt (lm/W)

Explanation: The luminous flux is divided by the efficacy to determine the electrical power needed to produce that amount of light.

3. Importance of Lumens to Watts Conversion

Details: Modern lighting uses lumens to measure brightness while watts measure energy consumption. This conversion helps evaluate energy efficiency.

4. Using the Calculator

Tips: Enter the luminous flux in lumens and luminous efficacy (default 16 lm/W for incandescent). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is luminous efficacy?
A: It measures how efficiently a light source produces visible light (lumens per watt of electricity).

Q2: What are typical efficacy values?
A: Incandescent: 10-17 lm/W, Halogen: 12-22 lm/W, CFL: 40-70 lm/W, LED: 60-120+ lm/W.

Q3: Why convert lumens to watts?
A: To compare energy efficiency between different lighting technologies or estimate power requirements.

Q4: How do I find the lumens of a light bulb?
A: Check the packaging or manufacturer specifications (replaces wattage ratings on modern bulbs).

Q5: Does higher efficacy mean better lighting?
A: Higher efficacy means more energy-efficient, but color quality and other factors also matter for lighting quality.